summaryrefslogtreecommitdiffstats
path: root/drivers/media/dvb/dvb-core/dvb_ringbuffer.c
blob: 77ad2410f4d3cd29cfb3a63a72c6dd6512c22cba (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
/*
 *
 * dvb_ringbuffer.c: ring buffer implementation for the dvb driver
 *
 * Copyright (C) 2003 Oliver Endriss
 * Copyright (C) 2004 Andrew de Quincey
 *
 * based on code originally found in av7110.c & dvb_ci.c:
 * Copyright (C) 1999-2003 Ralph  Metzler
 *                       & Marcus Metzler for convergence integrated media GmbH
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either version 2.1
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */



#define __KERNEL_SYSCALLS__
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/string.h>
#include <asm/uaccess.h>

#include "dvb_ringbuffer.h"

#define PKT_READY 0
#define PKT_DISPOSED 1


void dvb_ringbuffer_init(struct dvb_ringbuffer *rbuf, void *data, size_t len)
{
	rbuf->pread=rbuf->pwrite=0;
	rbuf->data=data;
	rbuf->size=len;

	init_waitqueue_head(&rbuf->queue);

	spin_lock_init(&(rbuf->lock));
}



int dvb_ringbuffer_empty(struct dvb_ringbuffer *rbuf)
{
	return (rbuf->pread==rbuf->pwrite);
}



ssize_t dvb_ringbuffer_free(struct dvb_ringbuffer *rbuf)
{
	ssize_t free;

	free = rbuf->pread - rbuf->pwrite;
	if (free <= 0)
		free += rbuf->size;
	return free-1;
}



ssize_t dvb_ringbuffer_avail(struct dvb_ringbuffer *rbuf)
{
	ssize_t avail;

	avail = rbuf->pwrite - rbuf->pread;
	if (avail < 0)
		avail += rbuf->size;
	return avail;
}



void dvb_ringbuffer_flush(struct dvb_ringbuffer *rbuf)
{
	rbuf->pread = rbuf->pwrite;
}



void dvb_ringbuffer_flush_spinlock_wakeup(struct dvb_ringbuffer *rbuf)
{
	unsigned long flags;

	spin_lock_irqsave(&rbuf->lock, flags);
	dvb_ringbuffer_flush(rbuf);
	spin_unlock_irqrestore(&rbuf->lock, flags);

	wake_up(&rbuf->queue);
}



ssize_t dvb_ringbuffer_read(struct dvb_ringbuffer *rbuf, u8 *buf, size_t len, int usermem)
{
	size_t todo = len;
	size_t split;

	split = (rbuf->pread + len > rbuf->size) ? rbuf->size - rbuf->pread : 0;
	if (split > 0) {
		if (!usermem)
			memcpy(buf, rbuf->data+rbuf->pread, split);
		else
			if (copy_to_user(buf, rbuf->data+rbuf->pread, split))
				return -EFAULT;
		buf += split;
		todo -= split;
		rbuf->pread = 0;
	}
	if (!usermem)
		memcpy(buf, rbuf->data+rbuf->pread, todo);
	else
		if (copy_to_user(buf, rbuf->data+rbuf->pread, todo))
			return -EFAULT;

	rbuf->pread = (rbuf->pread + todo) % rbuf->size;

	return len;
}



ssize_t dvb_ringbuffer_write(struct dvb_ringbuffer *rbuf, const u8 *buf, size_t len)
{
	size_t todo = len;
	size_t split;

	split = (rbuf->pwrite + len > rbuf->size) ? rbuf->size - rbuf->pwrite : 0;

	if (split > 0) {
		memcpy(rbuf->data+rbuf->pwrite, buf, split);
		buf += split;
		todo -= split;
		rbuf->pwrite = 0;
	}
	memcpy(rbuf->data+rbuf->pwrite, buf, todo);
	rbuf->pwrite = (rbuf->pwrite + todo) % rbuf->size;

	return len;
}

ssize_t dvb_ringbuffer_pkt_write(struct dvb_ringbuffer *rbuf, u8* buf, size_t len)
{
	int status;
	ssize_t oldpwrite = rbuf->pwrite;

	DVB_RINGBUFFER_WRITE_BYTE(rbuf, len >> 8);
	DVB_RINGBUFFER_WRITE_BYTE(rbuf, len & 0xff);
	DVB_RINGBUFFER_WRITE_BYTE(rbuf, PKT_READY);
	status = dvb_ringbuffer_write(rbuf, buf, len);

	if (status < 0) rbuf->pwrite = oldpwrite;
	return status;
}

ssize_t dvb_ringbuffer_pkt_read(struct dvb_ringbuffer *rbuf, size_t idx,
				int offset, u8* buf, size_t len, int usermem)
{
	size_t todo;
	size_t split;
	size_t pktlen;

	pktlen = rbuf->data[idx] << 8;
	pktlen |= rbuf->data[(idx + 1) % rbuf->size];
	if (offset > pktlen) return -EINVAL;
	if ((offset + len) > pktlen) len = pktlen - offset;

	idx = (idx + DVB_RINGBUFFER_PKTHDRSIZE + offset) % rbuf->size;
	todo = len;
	split = ((idx + len) > rbuf->size) ? rbuf->size - idx : 0;
	if (split > 0) {
		if (!usermem)
			memcpy(buf, rbuf->data+idx, split);
		else
			if (copy_to_user(buf, rbuf->data+idx, split))
				return -EFAULT;
		buf += split;
		todo -= split;
		idx = 0;
	}
	if (!usermem)
		memcpy(buf, rbuf->data+idx, todo);
	else
		if (copy_to_user(buf, rbuf->data+idx, todo))
			return -EFAULT;

	return len;
}

void dvb_ringbuffer_pkt_dispose(struct dvb_ringbuffer *rbuf, size_t idx)
{
	size_t pktlen;

	rbuf->data[(idx + 2) % rbuf->size] = PKT_DISPOSED;

	// clean up disposed packets
	while(dvb_ringbuffer_avail(rbuf) > DVB_RINGBUFFER_PKTHDRSIZE) {
		if (DVB_RINGBUFFER_PEEK(rbuf, 2) == PKT_DISPOSED) {
			pktlen = DVB_RINGBUFFER_PEEK(rbuf, 0) << 8;
			pktlen |= DVB_RINGBUFFER_PEEK(rbuf, 1);
			DVB_RINGBUFFER_SKIP(rbuf, pktlen + DVB_RINGBUFFER_PKTHDRSIZE);
		} else {
			// first packet is not disposed, so we stop cleaning now
			break;
		}
	}
}

ssize_t dvb_ringbuffer_pkt_next(struct dvb_ringbuffer *rbuf, size_t idx, size_t* pktlen)
{
	int consumed;
	int curpktlen;
	int curpktstatus;

	if (idx == -1) {
	       idx = rbuf->pread;
	} else {
		curpktlen = rbuf->data[idx] << 8;
		curpktlen |= rbuf->data[(idx + 1) % rbuf->size];
		idx = (idx + curpktlen + DVB_RINGBUFFER_PKTHDRSIZE) % rbuf->size;
	}

	consumed = (idx - rbuf->pread) % rbuf->size;

	while((dvb_ringbuffer_avail(rbuf) - consumed) > DVB_RINGBUFFER_PKTHDRSIZE) {

		curpktlen = rbuf->data[idx] << 8;
		curpktlen |= rbuf->data[(idx + 1) % rbuf->size];
		curpktstatus = rbuf->data[(idx + 2) % rbuf->size];

		if (curpktstatus == PKT_READY) {
			*pktlen = curpktlen;
			return idx;
		}

		consumed += curpktlen + DVB_RINGBUFFER_PKTHDRSIZE;
		idx = (idx + curpktlen + DVB_RINGBUFFER_PKTHDRSIZE) % rbuf->size;
	}

	// no packets available
	return -1;
}



EXPORT_SYMBOL(dvb_ringbuffer_init);
EXPORT_SYMBOL(dvb_ringbuffer_empty);
EXPORT_SYMBOL(dvb_ringbuffer_free);
EXPORT_SYMBOL(dvb_ringbuffer_avail);
EXPORT_SYMBOL(dvb_ringbuffer_flush);
EXPORT_SYMBOL(dvb_ringbuffer_flush_spinlock_wakeup);
EXPORT_SYMBOL(dvb_ringbuffer_read);
EXPORT_SYMBOL(dvb_ringbuffer_write);
EXPORT_SYMBOL(dvb_ringbuffer_pkt_write);
EXPORT_SYMBOL(dvb_ringbuffer_pkt_read);
EXPORT_SYMBOL(dvb_ringbuffer_pkt_dispose);
EXPORT_SYMBOL(dvb_ringbuffer_pkt_next);